Naturalist 25th Anniversary Edition

by Edward O. Wilson

  The next day, working south off the coastal road near Korovou, I learned another melancholy fact about conservation. In a small patch of what appeared to be natural forest I found only exotic ant species. I realized that on islands harboring native species of limited diversity, the ecosystems are vulnerable to invasion by aliens even if left physically intact. Much of the Pacific fauna has gone under in the path of pigs, goats, rats, Argentine ants, beard grass, and other highly competitive forms introduced by human commerce. Strangers have savaged the islands of the world.

  I did not linger in Fiji. The ant fauna was already reasonably well known, thanks to Mann’s lengthy residence. The next day I caught the Qantas flying boat from Suva to Noumea, the French colonial center of New Caledonia.

  Mount Mou, New Caledonia, December 1954. With my arrival in New Caledonia, I had reached what I would thereafter consider my favorite island, a large, pencil-shaped land 1,200 kilometers off the east coast of Australia, the southernmost reach of Melanesia. The very name of the place meant, and still means, “alien” and “distant” to me. I knew from the work of previous naturalists that plants and animals had come to its shores during millions of years, for the most part eastward from Australia and southward from the Solomon Islands through the New Hebrides. They had mingled and evolved to form unique ecosystems. Among the native species were archaic trees and other plants, a few of ultimate Gondwanaland origin, whose ancestors had lived as far afield as Antarctica, when warmer climates prevailed. Also present were stocks of animals and plants that have evolved into extreme forms found nowhere else, including the famous kagu, representing an entire family of birds, the Rhynchochetidae. This flightless endemic, its shrill call piercing the night, had been reduced to near extinction since the French colonized the island in the 1860s. Early records indicated that the same broad biogeographic pattern of mixed origin and endemicity, with extreme rarity for some species, held for ants. I intended to find out.

  On one hot day in this austral midsummer I caught the northbound bus from Noumea and got off at the little village of Païta. I hiked six kilometers up a small dirt road to the estate of a family named Bourdinet and dropped my gear at the gazebo, where I set up camp. The Bourdinets were not home that week and could offer no other accommodation. No matter; I was happy to concentrate entirely on my work. I walked another kilometer to the house of the Pentecost family, their nearest neighbors, climbing in the process to 300 meters elevation. My goal was the summit ridge forest of Mount Mou rising beyond, to 1,220 meters. To get there I pushed my way through a broad thicket of dense, dry bracken. When I reached the western crest of the ridge, I found myself still in the midst of bracken. But at least I had broken out onto the summit trail. The going grew easier, and the forested mountaintop was in full view only a kilometer away.

  Because I was completely alone and had seen no one since Païta, it occurred to me that if I were crippled in an accident it would be three or four days before my contacts in Noumea became aware that anything was wrong. I stepped more carefully for the rest of the climb. As newly gathering mountaintop mist closed around me, I entered the forest. There I encountered first low shrubs and scattered trees, then continuous stands of Araucaria and Podocarpus conifers, their trunks and branches laden with mosses and other epiphytes. A little farther on, near the summit, I entered the true cloud forest. Here the trees were gnarled and stunted, and their canopies closed overhead at only ten meters. Their trunks and the surface of the soil in which the trees grew were coated with an unbroken blanket of wet moss.

  I had arrived on an island within an island, a world of my own. The warm proprietary feeling of my boyhood flooded back. My imagination drifted back across epochs. The conifers there were ancient members of the Antarctic realm, still distributed across southern Australia, New Zealand, temperate South America, and here, the uplands of New Caledonia. Some of the species of plants and animals dated back to the Mesozoic Era, when they were surely browsed by dinosaurs, and when parts of the Antarctic continent itself were still habitable by all. As I began hunting ants, a little green parrot with a red cap landed on a branch close by and stayed there. At intervals he squawked at me in some mysterious psittacine language. We were perfect companions in the mossy forest, native and exotic joined in momentary harmony. I would do no harm, I told the parrot, and leave soon, but this place would live forever in my memory.

  Not just the ants but everything I saw, every species of plant and animal, was new to me. These creatures were a fully alien biota, and it is time to confess: I am a neophile, an inordinate lover of the new, of diversity for its own sake. In such a place everything is a surprise, and I could make a discovery of scientific value anytime I wished. My archetypal dream came clear:

  Take me, Lord, to an unexplored planet teeming with new life forms. Put me at the edge of virgin swampland dotted with hummocks of high ground, let me saunter at my own pace across it and up the nearest mountain ridge, in due course to cross over to the far slope in search of more distant swamps, grasslands, and ranges. Let me be the Carolus Linnaeus of this world, bearing no more than specimen boxes, botanical canister, hand lens, notebooks, but allowed not years but centuries of time. And should I somehow tire of the land, let me embark on the sea in search of new islands and archipelagoes. Let me go alone, at least for a while, and I will report to You and loved ones at intervals and I will publish reports on my discoveries for colleagues. For if it was You who gave me this spirit, then devise the appropriate reward for its virtuous use.

  Ciu, near Mount Canala, New Caledonia, December 1954. I had to go to what seemed the edge of nowhere in order to sample ants on the northern coast, in moist lowland and foothills forest. The insects were likely to belong to different species from those around Noumea and might include at least two rare endemic genera taken by earlier collectors. I had risen at 3:45 in the morning to catch the daily bus to Canala. The antique vehicle followed a route that wound 170 kilometers across the central massif of the island. The driver made countless detours and stops to pick up and drop off native New Caledonians. We arrived at Canala at 10:30 in a driving rain that continued for the rest of the day. I lunched at the Hotel de Canala, tumbled into bed, and dreamed of blue skies as I fell asleep.

  Canala in 1954 was a collection of twenty rundown houses, the hotel, and a Catholic mission. The marquee social activity of the village was cricket played by men and women on the same teams, supported by cheerleaders who beat bamboo sticks together. The glamor ended there. The Hôtel de Canala contained a kitchen, a dining room, and a row of six square cubicles, each three meters on a side and furnished with a bed, table, and water basin. Lodging was U.S. $4.80 a night. The cubicle next to mine was the entertainment parlor of a prostitute who practiced her trade very noisily. All the guests used the same shower and evil-smelling outhouse. Meals were of uncertain provenance and often inexplicably cold, but I didn’t care. Dinner was only $1.60 with wine, and all I wanted anyway was enough nourishment to fuel me to the nearby forests and back free of dysentery.

  The next morning, packing a sandwich and a bottle of diluted red wine, I walked the one-lane dirt road seven kilometers south to Ciu, an aggregate of farms on the edge of the inland forest. For part of this distance the road passed through a marsh, from which clouds of striped Aedes mosquitoes poured through the hot sunlight like sniper bullets. In the manner of Aedes in other parts of the world, they commenced biting as soon as they landed on a patch of bare skin. The repellant I splashed on myself meant little to them. I named this stretch of the road Mosquito Alley, and started to jog-walk its length, head down and arms folded like a man running a gauntlet.

  My destination was the Fèré farm, bordered by a small river of the size we call a creek in Alabama. I followed once again the universal formula for gaining access to tropical forest: crawl through a barbed-wire fence, walk across a cow pasture, wade a shallow part of the river (in this case adorned by an upstream waterfall), and climb a hillside into the forest. The effort proved wo
rth the trouble. I soon entered the shade of native timber, a prehistoric New Caledonian world. I had passed no one on the Canala-Ciu road, and as I worked back into the forest I could see no sign of recent human disturbance. The solitude, as usual, felt right. Human beings mean comfort, but they also mean a loss of time for a field biologist, a break in concentration and, for strangers in an unknown land, always a certain amount of personal risk.

  The Fèré tract was not a true rain forest in the familiar, Amazonian sense. It comprised only two stories of trees, with the upper canopy twenty meters high and broken in enough places to let sunshine fall in large, radiant patches on the forest floor. The habitat was ideal for ants. It abounded with pure New Caledonian species, many new to science. I was struck by the prevalence of red-and-black coloration among the workers foraging above ground. At Chapeau Gendarme near Noumea the same species were predominantly yellow. What was the meaning of this local color code? Perhaps it was just coincidence. But I suspected mimicry. My guess was that one to several of the species were poisonous, as I had supposed to be true of the metallescent ants of Cuba. The bright and distinctive color says to potential visual predators such as birds and lizards: Don’t even try to eat me, you’ll be sorry. In theory it pays for all the local poisonous species to evolve the same color, forming a consortium among the advertisers. It also pays for harmless, tasty species to acquire the same appearance and enjoy a free ride on the repellant forms they imitate. I had neither the means nor the time, however, to test either hypothesis.

  My attention soon shifted to a phenomenon that was more tractable to immediate study and would later prove important in tracing certain aspects of ant evolution. Near Noumea I had collected the first ants of the genera Cerapachys and Sphinctomyrmex and hence of the entire ant tribe Cerapachyini ever recorded from New Caledonia. Here at Ciu they were so abundant I could observe them within the first hours of my arrival. I discovered that the peculiarly cylindrical, hard-bodied workers feed on other ants. To overcome their formidable prey, they hunt in packs much like the army ants of the mainland tropics. Their sorties, I saw, are much smaller and less well organized yet also effective in breaking down the defenses of the target colonies. “Real” army ants, the kind that march in thick columns in Asia and Australia, never managed to cross the Coral Sea and colonize New Caledonia. The less spectacular cerapachyines somehow succeeded, and even though they are less formidable huntresses they have the army ant niche to themselves. That is why, I conjectured, they are so abundant on New Caledonia and so rare on most continents. The concept was ill-formed in my mind then. I recorded the habits of the cerapachyine ants only because they are interesting in their own right. But three years later I would use the field notes as a key piece in my reconstruction of the evolutionary origin of army ants.

  Ratard Plantation, Luganville, Espiritu Santo, New Hebrides, January 1955. Curiosity and opportunism brought me to this most remote and least-known large island of all the South Pacific. Still mostly covered by undisturbed rain forest, the northern New Hebrides had never been collected for ants, so every record I put in my notebook would be new. Even a brief glimpse of the fauna as a whole might allow me to place the New Hebrides (now the republic of Vanuatu) in the larger biogeographic picture. The archipelago is a potential stepping-stone to the more distant islands of the western Pacific. It can receive both Asian elements from the fully tropical Solomon Islands, to the north, and Australian elements from subtropical New Caledonia, to the south.

  On this day, however, my exploration had been cut short. I was in bed with a high fever; the opening strains of Swan Lake ran inexplicably through my head, over and over, scrambling my thoughts into chaos. To add to my distress, I was occasionally bounced by aftershocks of an earthquake that had struck from an epicenter near Malekula three days earlier. Several large circular bruises were spaced at regular intervals across my chest. They had been inflicted by a doctor—he claimed he was a doctor—in Luganville in an attempt to draw the fever out with powerful suction cups. Surely I was one of the last patients in the Western world to endure this archaic and useless remedy.

  My hosts were Aubert Ratard, his wife, Suzanne, and their two teenage sons. The Ratards were among the wealthiest of the two hundred French families who owned copra plantations on Espiritu Santo. Down the road from their coastline property were an airstrip and Quonset huts, remnants of an American base from the Second World War. The American forces and the people of the New Hebrides were the inspiration for James Michener’s Tales of the South Pacific. Michener had also been a houseguest of the Ratards a decade earlier, and Ratard himself was the inspiration for the French planter in the book and musical. At dinner Aubert told me about the real Bloody Mary, who still lived in the central administrative town of Vila, on the island of Éfaté. From the shore of his property he pointed to Bali-ha’i across the Segond Channel, in real life the island of Malo.

  Literary history was forgotten when I turned my attention to the wilderness that surrounded us. Soon after arriving and before falling ill, I walked into lush rain forest that reached all the way to the sandy beach, a rarity in the overpopulated tropics. It was home to undisturbed flocks of parrots and crowing jungle fowl, the wild ancestral species of the domestic chicken. Flying foxes, giant fruit-eating bats, flapped leisurely above the treetops. I soon fixed the affinities of the ant species I found there: Melanesian, as expected, Solomon Islands most likely, hence ultimately Asian. I made a general observation on the ecology of these insects that would find a place in my later synthesis of island evolution. It is as follows. Relatively few species of ants inhabit Espiritu Santo; the island is just too distant and geologically young to have received many immigrants. Freed from heavy competition, some of the colonists have dramatically increased their niche; they occur in dense populations across a wide range of local environments and nest sites. I would later call this phenomenon “ecological release,” and help to establish it as an important early step in the proliferation of biodiversity.

  Esperance to Mount Ragged, Western Australia, January-February 1955. I disliked leaving Espiritu Santo just when I had begun to study its fauna, but now I had to go to Australia for a potentially even more important excursion scheduled some months earlier. I took the weekly Qantas flying boat back to Noumea, then to Sydney and, after a brief stay in the city and a collecting excursion into the surrounding countryside, flew on to Kalgoorlie. From this inland center of Western Australia’s sheep country, I proceeded south by rail to Norseman for a round of ant collecting. At a local bar I fell in with a group of construction workers, who invited me to collect ants out at their workplace in the nearby eucalyptus scrub. A full day in the bush completely dehydrated me; two months in the humid tropics had rendered my system unable to handle evaporation in such a hot, semidesert environment. When we arrived back at the bar late that afternoon, I chugalugged four beers in a row. My hosts, themselves heavy consumers in a country known for Olympic-class beer drinking, were impressed. So was I: I am normally a one-beer-maximum occasional drinker.

  I then went farther south to Esperance, an isolated coastal town just west of the Great Australian Bight. Here I was joined by Caryl Haskins, a fellow entomologist and the newly appointed president of the Carnegie Institution of Washington. This outpost was our point of departure on a quest for the grail of ant studies. A hundred kilometers to the east, out across the sandplain heath, lived the grail: Nothomyrmecia macrops, the most primitive known ant, a lost species since its discovery twenty-three years before, and quite possibly the key to the origin of social life in ants. We meant to rediscover the species and be the first to study it in life.

  Before departing, we decided to look for ants around Esperance. We walked out of the small town to the top of nearby Telegraph Hill, a low granitic rise covered by woody shrubs and patches of open gravelly soil ideal for ant nests. We stood quietly for a while admiring the long sweep of bush-covered land down to Esperance Bay, where huge combers thundered in from Antarctica. Out on t
he horizon were scattered islands of the uninhabited Recherche Archipelago. We had been told they were home to dense populations of poisonous elapine snakes. Great white sharks were known to be common in the blue-black waters. We were a long way from home, as far as it was possible to be from Boston, and Renee, and remain on land.

  Telegraph Hill and its environs were strange and beautiful to behold, but not comfortable. January is the hottest month of the year. Just four days previously the temperature in Esperance had reached 41° Celsius (106°F). On the day of our excursion, the sun beat down from a nearly cloudless sky, and a hard dry wind blew in from the mainland semidesert behind us. Bush flies, aggressive relatives of house flies, swarmed around our heads, ran about on our ears and faces, and attempted to feed on the moisture of our eyes, nostrils, and mouths. We responded by continuously performing the “Australian salute,” a wave of the hand around the head to chase bush flies away.

  Caryl set out at once to collect colonies of bulldog ants, his favorite insects. This was no casual undertaking. The workers, measuring up to three centimeters in length, possess large bulging eyes with excellent vision, long saw-toothed mandibles, and painful stings. They are among the most belligerent insects in the world. Imagine a crater nest one to two meters across, with an opening in the center several centimeters wide, from which come and go dozens of surly red-and-black ants the size of hornets. Disturb them in the slightest and they charge you fearlessly. A few will follow your retreat for as much as ten meters from the nest. These ants, in short, are not the furtive picnic and kitchen raiders of America.

  Caryl showed me how to gather entire bulldog ant colonies without risking one’s life in the process. One needs a bit of courage and a willingness to endure pain. He went straight at the nest, snatching up each attacking ant closest to him and popping it into a large bottle—quickly, before it had a chance to curl its abdomen around and sting him. Usually the method worked, but occasionally a charging worker climbed onto his ankle or forearm and nailed him before he could brush it away. When all the outside guards had been cleared off, he started to dig into the entrance hole. More angry workers poured out, only to join their nestmates in the bottle. Caryl continued until he had excavated a shaft a meter or so below the surface where, in every case, he found the mother queen hiding in one of the deepest nest chambers. He walked away with each colony clean and healthy, ready for transport back to the United States and laboratory study.